Hello,

the problem here is that the ACK has Route headers and looks like the ACK inside dialog.

The 407 is for a re-INVITE, so the To-tag is present, it is not generated by sl module to be able to filter it out. It gets to config where the requests are routed using loose_route() like a request part of a dialog.

I haven't checked the specs right not for a 100% accurate answer, but ACK for a failure code is hop-by-hop, it should have no Route headers, being intended for next hop only, and I expect most UA implementation do it like this, not having similar reports in more or less 20 years.

If the ACK will be without Route headers, it should be stopped locally. You can try to play with the order of checks for transaction and use of other tm functions to detect such case (eventually combined with htable) and drop the ACK.

Cheers,
Daniel

On 07.05.20 17:10, Denys Pozniak wrote:
Hello!

I have some misunderstanding regarding the processing of SIP ACK on local Kamailio 4xx reply (eg 407 Proxy Authentication Required).
In the picture below you can see that such a message just goes through the proxy and moreover gets into the request_route section.
I expect this SIP ACK to be consumed by the sl module without hitting script logic.



I put the part below to the very top of the request_route section:

request_route {

if ( is_method("ACK") ) {
        t_check_trans();
        $var(error) = $rc;
        xlog("L_ERR", "[CATCH_ACK] m=$rm cseq=$cs ru=$ru err=$var(error) [$ci]");
}
....

And as a result, I detected in syslog:

May  7 16:15:34 test-edge /usr/sbin/kamailio[11642]: ERROR: <script>: [CATCH_ACK] m=ACK cseq=153 ru=sip:mod_sofia@10.0.7.3:5060 err=-1 [051e7c50-0b10-1239-2996-001dd8b71cb2]

SIP re-INVITE (hold) from Phone:

2020/05/07 16:15:34.629973 176.6.4.6:1024 -> 185.9.7.7:5060
INVITE sip:mod_sofia@10.0.7.3:5060 SIP/2.0
Via: SIP/2.0/UDP 192.168.11.111:5060;branch=z9hG4bK00475de2da8eea118ec67caaaddc98fb;rport
Route: <sip:185.9.7.7;r2=on;lr=on;did=f98.f3f4>
Route: <sip:10.0.7.5;r2=on;lr=on;did=f98.f3f4>
Route: <sip:10.0.7.6;lr=on;did=f98.fbe>
From: <sip:312222222222@10.0.7.6>;tag=00dfd3d8da8eea118ec67caaaddc98fb
To: "Denys VOIP" <sip:5008@185.9.7.7>;tag=54Q0XNHgXBUvp
Call-ID: 051e7c50-0b10-1239-2996-001dd8b71cb2
CSeq: 153 INVITE
Contact: <sip:312222222222@192.168.11.111:5060;gr=00DCB21F-BD8E-EA11-8E88-7CAAADDC98FB>
Content-Type: application/sdp
Allow: INVITE, ACK, BYE, CANCEL, INFO, MESSAGE, NOTIFY, OPTIONS, REFER, UPDATE, PRACK
Max-Forwards: 70
Supported: 100rel, replaces, from-change, gruu
User-Agent: SIPPER for PhonerLite
Content-Length:   313

v=0
o=- 3858283927 2 IN IP4 192.168.11.111
s=SIPPER for PhonerLite
c=IN IP4 192.168.11.111
t=0 0
m=audio 5062 RTP/AVP 8 0 9 107 101
a=rtpmap:8 PCMA/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:9 G722/8000
a=rtpmap:107 opus/48000/2
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=ssrc:782125221
a=sendonly

SIP 407 from Kamailio:

2020/05/07 16:15:34.632298 185.9.7.7:5060 -> 176.6.4.6:1024
SIP/2.0 407 Proxy Authentication Required
Via: SIP/2.0/UDP 192.168.11.111:5060;branch=z9hG4bK00475de2da8eea118ec67caaaddc98fb;rport=1024;received=176.6.4.6
From: <sip:312222222222@10.0.7.6>;tag=00dfd3d8da8eea118ec67caaaddc98fb
To: "Denys VOIP" <sip:5008@185.9.7.7>;tag=54Q0XNHgXBUvp
Call-ID: 051e7c50-0b10-1239-2996-001dd8b71cb2
CSeq: 153 INVITE
Proxy-Authenticate: Digest realm="185.9.7.7", nonce="XrQaXjfjyrftyrtiyrft7uO"
Server: kamailio (5.2.2 (x86_64/linux))
Content-Length: 0

SIP ACK from Phone:

2020/05/07 16:15:34.672872 176.6.4.6:1024 -> 185.9.7.7:5060
ACK sip:mod_sofia@10.0.7.3:5060 SIP/2.0
Via: SIP/2.0/UDP 192.168.11.111:5060;branch=z9hG4bK00475de2da8eea118ec67caaaddc98fb;rport
Route: <sip:185.9.7.7;r2=on;lr=on;did=f98.f3f4>
Route: <sip:10.0.7.5;r2=on;lr=on;did=f98.f3f4>
Route: <sip:10.0.7.6;lr=on;did=f98.fbe>
From: <sip:312222222222@10.0.7.6>;tag=00dfd3d8da8eea118ec67caaaddc98fb
To: "Denys VOIP" <sip:5008@185.9.7.7>;tag=54Q0XNHgXBUvp
Call-ID: 051e7c50-0b10-1239-2996-001dd8b71cb2
CSeq: 153 ACK
Content-Length: 0

SIP ACK (unwanted) from Kamailio to Core:

2020/05/07 16:15:34.675546 10.0.7.5:5060 -> 10.0.7.6:5060
ACK sip:mod_sofia@10.0.7.3:5060 SIP/2.0
Max-Forwards: 10
Via: SIP/2.0/UDP 10.0.7.5;branch=z9hG4bK0d46.c33c3556c3cffbac49e717352b3575f6.0
Via: SIP/2.0/UDP 192.168.11.111:5060;received=176.6.4.6;branch=z9hG4bK00475de2da8eea118ec67caaaddc98fb;rport=1024
Route: <sip:10.0.7.6;lr=on;did=f98.fbe>
From: <sip:312222222222@10.0.7.6>;tag=00dfd3d8da8eea118ec67caaaddc98fb
To: "Denys VOIP" <sip:5008@185.9.7.7>;tag=54Q0XNHgXBUvp
Call-ID: 051e7c50-0b10-1239-2996-001dd8b71cb2
CSeq: 153 ACK
Content-Length: 0
loose-route: done

IP addresses and call-flow:
Core (10.0.7.6) --> [ Kamailio (10.0.7.5) -> Kamailio (185.9.7.7) ] --> Phone (176.6.4.6)

[root@test-edge kamailio]$ kamailio -v
version: kamailio 5.2.2 (x86_64/linux)
flags: STATS: Off, USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MEM, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLACKLIST, HAVE_RESOLV_RES
ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144 MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB
poll method support: poll, epoll_lt, epoll_et, sigio_rt, select.
id: unknown
compiled on 19:29:40 Jun 20 2019 with gcc 4.8.5



--

BR,
Denys Pozniak



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